(1) Field of the Invention
The present invention relates to a bonding body in which a first member and a second member are connected by means of adhesives, and particularly relates to a bonding body in which one or both of the first and second members is thin.
(2) Prior Art Statement
Generally, various types of bonding bodies in which the first member and the second member are connected by means of the adhesives are known. Moreover, various kinds of adhesives used for this purpose are also known. As the normal adhesives, epoxy resin, acrylate resin, polyurethane resin, polyimide resin and silicone resin are known.
Among the adhesives mentioned above, in order to obtain a bonding body in which one of or both of the members are very thin, it is necessary to control precisely a thickness of the adhesive layer and a thickness variation of the adhesive layer, and also it is necessary to exhibit a sufficient bonding strength. In the normal adhesives mentioned above, it is difficult to have these two properties i.e. a thickness controlling property and a sufficient strength.
For example, the epoxy resin exhibits a high bonding strength. However, if it is used as the adhesive layer, it generates a thickness variation of the adhesive layer since it has a large viscosity. Therefore, it is not possible to obtain the adhesive layer having a uniform thickness. In this case, when the member of the bonding body using the epoxy resin as the adhesive layer is ground or polished to have a thin member, there is a drawback such that a thickness variation of the member occurs. The acrylate resin forms the adhesive layer having a uniform thickness since it has a low viscosity. However, when the member of the bonding body using an acrylate resin is ground or polished to have a thin member, a fracture or a peel-off of the member occurs. Therefore, it is not possible to obtain the member having a thickness of not more than 10 μm. Moreover, when the members each having a different thermal expansion coefficient are connected by heat so as to harden them, there is also a drawback such that the bonding body is bent due to a stress generated from a thermal expansion coefficient difference of the members.